This invention relates to the curing of an acrylate, ethylene/acrylate, or ethylene/methacrylate/acrylate polymer with diamines in the presence of certain acid catalysts.
Ethylene/acrylate or ethylene/methacrylate/acrylate polymers can be cured with free radical systems as described in U.S. Pat. No. 3,873,494, to K. J. Lewis. However, amine cures are preferred for acrylate-based polymers because they give vulcanizates with desirable properties such as low compression set, high tensile strength, and good heat aging. Also, amine vulcanization of these polymers may not require the presence of a cure site monomer in the polymer and this is desirable in terms of economy and synthesis.
U.S. Pat. No. 2,579,492, to J. E. Hansen and T. J. Dietz, describes the vulcanization of an acrylate-containing polymer with polymethylene or polyethylene diamines in the presence of a fatty acid which contains 8-18 carbon atoms. However, large amounts of the diamine are required and the rate of vulcanization is very slow. By employing the methods of the present invention, it is now possible to vulcanize acrylate, ethylene/acrylate, or ethylene/methacrylate/acrylate polymers with diamines at a much more rapid rate and with the use of smaller quantities of diamine.